Sprayer Problems - Black Specks In Finish


From original questioner:

Hi, I am currently using a air assisted C.A technologies bobcat sprayer. I have a small custom cabinet shop and spray booth . This is my problem, I will spray my white vinyl lacquer sealer, get a beautiful finish, switch to my cab acrylic clear coat(sherwinn williams product) then ill notice it will spit out little black specks or looks like little hairs on the finish, this is so frustrating. What should i do to fix this, I have been running lacquer thinner through it, to clean the system, maybe I just need to do it longer? It only does it when spraying the clear coat, I don't know any ideas would be helpful.

From contributor Le

Are you thinning the CAB finish?

From contributor Cr

I have noticed that my black Binks fluid hoses breakdown over time (a year or two if I don't replace them sooner), and will start spitting out small black bits of the hose lining into the finish. Could be your problem too? Not sure why it would only be the clear and not the pigmented though

From contributor Gf

I have thought about this, my hose is 1/8"
yellow hose, maybe the inside is black, or maybe Im just getting dust nibs, I guess what I'm going to do next is spray them upright , and hang them close to the fan, if I'm still getting them, then i know its coming from the hose or out of my gun. Some time ago I sprayed some black lacquer through my system, do you think there could be some residue left over even though I've cleaned my lines out repeatedly?

From contributor Bo

If you suspect the hose, buy a cheap inline fluid filter and place between gun and hose - you'll know if that's the issue real quick.

From contributor Gf

thanks for the tip, i do have a filter right on the end of my gun where the fluid line screws in. These particles are very very small, unnoticeable to the untrained eye,but I'm also getting what looks like very small fuzz or what looks like very small pieces of hair in it as well, I have only been spraying my own finishes for about 8 months so I have so many things I just don't know for lack of experience, I feel like its just so close to being perfect, and now i am down to this , its driving me bonkers.

From contributor Le

NOt sure about the black specs, but hose deterioration sounds as good as anything, but the hairs can be a problem with spraying a coating that needs a bit more thinner.

From contributor Gf

What are the black hairs, resulting from not thinning enough?

From contributor Le

Not enough thinner can cause stringing aka hairs. Can't say anything about the black specks.

From contributor ri

Do you use steel wool around the acrylic? Rusted steel wool particles?

From contributor Sh

Find the source of your problem by process of elimination.... First since your dealing with small amounts of coating, you should be straining your material before it goes in your gun, or spray pot, etc etc.... Take 3 fine grade cone funnels and strain your material into a very clean container... ok? How much junk do you see in the strainers? Pour a little bit of solvent over the strainers with opaques to see what you strained out. Clean? ok.. You using a pressure pot system? Is the tank religiously clean? how about the lid on the pot? do you use liners? pour strained material into pot and remove the fluid line from the gun. Carefully pressurize the pot and let the material flow through the pot and hose through yet again 3 fine cone strainers into a clean container? Did you pick up garbage here? Do you break down your guns after every color change and complete scrub the passages?if it's not your material or your equiptment then it could be the atmosphere... even lint falling off your clothing can be a nightmare... wear a tyvek suit when you spray as ive seen blue fuzz from my shirt all over a white panel after topcoating.